Had some nasty deep scratches on the passenger side headlight of my M3, wet sanded it down starting with 320, then working my way down to 3000. Finished with a good polish and my DA polisher. When I was done, looked like there had never been any scratches there at all. Worked a treat. Just a word of warning, if you do wet sand, do not press too hard, let the paper do the sanding.